Flue Gas Desulfurization and Denitrification System

Flue Gas Desulfurization and Denitrification System is an integrated flue gas treatment arrangement used to reduce sulfur dioxide (SO₂) and nitrogen oxides (NOx) from combustion and industrial process gases. Different treatment units are combined according to the composition, temperature, flow rate, and pollutant concentration of the flue gas.

The treatment sequence can include particulate removal, temperature adjustment, denitrification, desulfurization, and final gas conditioning. The actual arrangement depends on the selected DeNOx and FGD processes and the characteristics of the emission source.

For denitrification, SCR or SNCR technology can be incorporated. SCR uses a catalyst together with a reducing agent, while SNCR introduces the reducing agent into a suitable high-temperature reaction zone without a catalyst.

For desulfurization, wet, dry, or semi-dry processes can be selected. In wet systems, the flue gas contacts an alkaline absorbent inside an absorber tower. Sulfur dioxide is transferred into the absorbent and converted through chemical reaction.

Gas conditioning equipment can be installed between different treatment stages. Demisters may be used after wet desulfurization to remove entrained liquid droplets, while fans and ductwork maintain the required gas flow through the treatment line.

System design is determined by flue gas volume, inlet temperature, SO₂ and NOx concentrations, dust loading, oxygen content, moisture, reagent properties, reaction temperature, and required treatment conditions.

Main Components

• Flue gas inlet

• Dust removal unit

• DeNOx reaction unit

• Reducing agent preparation system

• Reagent injection equipment

• SCR catalyst or SNCR reaction section

• FGD absorber

• Absorbent preparation and circulation system

• Spray system

• Mist eliminator

• Induced draft fan

• Ductwork

• Monitoring and control system

Treatment Process

1. Flue gas enters the treatment line.

2. Particulate matter is removed or reduced where required.

3. Gas temperature is adjusted according to the selected DeNOx process.

4. NOx is treated through SCR or SNCR.

5. SO₂ is removed through wet, dry, or semi-dry desulfurization.

6. Liquid droplets are separated after wet treatment.

7. Treated flue gas is discharged through the outlet.

Operating Factors

• Flue gas flow rate

• Gas temperature

• SO₂ concentration

• NOx concentration

• Dust concentration

• Reducing agent dosage

• Desulfurization reagent concentration

• Gas residence time

• Pressure drop

• Moisture content

Applications

• Power plant flue gas

• Industrial boilers

• Cement kilns

• Waste incineration

• Steel and metallurgical processes

• Chemical processing

• Industrial furnaces

• Combustion exhaust treatment